Acid Properties of HY Zeolite Dealuminated by Steaming and EDTA Treatment - NMR, XPS and IR Studies

Steaming of zeolite is known to remove some Al atoms from the framework, which results in the formation of extraframework Al species and in the increase of the framework Si/Al ratio (Si/Al fram). The effects of these factors on the nature, concentration, strength, homogeneity and accessibility of the acid sites in Y zeolite were followed by an IR study of the adsorption/desorption of ammonia and pyridine.